Refarming refers to re-planning of a spectrum resource, and generally means that a lower-standard system spares a spectrum band for a higher-standard system. For example, GL Refarming means that a Global System for Mobile Communications (GSM) system spares a spectrum band for an LTE system. By using an 850M/900M spectrum as an example, 850M/900M is originally provided for the GSM system to use, and to improve deep coverage of the LTE system, an operator spares a part of spectrums of the GSM system for the LTE system. Because existing spectrum resources are limited, the operator cannot provide a standard bandwidth for the LTE system. For example, the LTE system uses a standard 5M bandwidth, but the operator can provide only a 4.4M or 4.6M nonstandard bandwidth. A standard bandwidth of the LTE system is 1.4M, 3M, 5M, 10M, 15M, or 20M.
To enable the nonstandard bandwidth provided by the operator to be used in the LTE system, a transition band or a resource block (RB) of a spectrum is compressed in the prior art. By using a 4.6M nonstandard bandwidth as an example, a solution in the prior art is to use a 4.6M symmetric filter to filter a 5M bandwidth. As shown in FIG. 1, FIG. 1 is a spectrum compression solution in the prior art in which a 4.6M symmetric filter is used to perform symmetric filtering on a signal, and one RB is filtered out (black in FIG. 1 represents the RB that is filtered out) at each of two ends of a spectrum. By using a filter, a signal at a frequency outside a bandwidth of the filter is filtered out, and a bandwidth of a signal actually sent by a base station is 4.6M.
In the solution of the prior art, half an RB is filtered out at each of two ends of a spectrum by means of symmetric filtering, which makes two RBs unusable. Therefore, according to an existing technical solution, a waste of spectrum resources is caused.